I don't know - this is my first time hatching. But, I have read that they pip and something has to dry out before they can hatch, so my guess would be they take a rest.
It takes a lot of energy to get out, so a bit of rest is fine and normal.
Like all of Nature, the fittest survive the best.
Thanks! Well, we're off to bed. Here's hoping they are okay and I have a birthday present waiting for me in the incubator when I get up. (Bday isn't for another week, but still....)
Jennifer